1. Field of the Invention
The present invention concerns a pond filter which has a pre-filtering unit and is installed in a housing.
2. Description of the Related Art
A pond filter of this type is already known from the general state of the art. A pond filter of this type is usually placed on the bottom of a pond and is downstream of a pump that pumps water into the pond filter to clean the water. The pond filter contains a filtration unit that catches suspended material contained in the water to be cleaned and sometimes also performs a biological purification with the addition of filter aids. The clean water is then discharged back into the pond at a pond outlet. It is also well known that a pond filter of this type has a channel outlet, through which water is discharged when the pond filter is being cleaned in a flushing operation.
However, it has been found that the filtration unit becomes clogged relatively quickly in the filtration operation described above, even though the water coming from a pump has already been subjected to coarse filtration by a coarse filter at the pump. As a result, the filtration operation must be interrupted relatively frequently to clean the filtration unit. Frequent cleaning of the filtration unit is inconvenient, because it requires that the pond filter be removed from the pond.